The building was originally built in 1963 and renovated in 1995. The building features a heated floor area of 2112 m² on 5 floors with a total of 30 apartments. The building was renovated exchanging the windows with insulating glazing (Uwin = 1.7 W/m²K), and adding layers of thermal insulation (styrofoam, d = 60 mm, l = 0.035 W/mK) to the façade, cellar and to ceiling, thus reducing the overall U-value of the opaque envelope from Uenvelope = 1.71 W/m²K to 0.323 W/m²K.
Key facts
| Building | Heat pump and source | |||
| Location | Karlsruhe, Germany |
Number of HP | 1 | |
| Construction | 1965 | Installed power | 55.4 kW | |
| Heat distribution | radiator heating | Operation mode | bivalent | |
| Heated area | 2112 m² living | Heat source | PVT collectors (solar+ambient) |
|
| Level of insulation | good (renovation in 1995) |
|||
| Heating system | Domestic hot water | |||
| Heat demand | 60 kW | Type of system | central | |
| Heating temperature | 55 / 45 °C |
Max. temperature | 62 °C | |
| Circulation system | yes | |||
Description of the technical concept
Heat Pump Technology
- Cascade of two heat pumps with
27 kWth + 43 kWth - Viessmann 351.B27 and 351.B43
Heat Source
- Outdoor air unit: 40 kWth nominal power
- Ground source heat exchanger:
18 probes à 18 m length, double U tube, 30 kWth - Hydraulic source system developed within research project «HEAVEN» by Fraunhofer ISE and Fa. Viessmann.
→ Bivalent system with condensing gas boiler as back up (bivalent parallel operation)
→ Two drinking water storages (2x 850 l)
→ One heating buffer storage (850 l)
→ Heat pump integrated into district energy systems via SG ready to allow optimization of self-consumption of PV and CHP electricity
LowEx Measures
Heat Distribution System
- Original radiators are mostly sufficient to allow a reduction of nominal heating temperatures
- 13 of 150 radiators were identified as “bottleneck” radiators. These radiators are exchanged with radiators of larger heating power
- Reduction of heating temperatures to 55/45°C
- Hydronic balance
Drinking water distribution
- Two external freshwater stations
- Circulation
